High molecular weight linear polyesters and copolyesters of glycols and terephthalic or isophthalic acid are described in, for example, U.S. Pat. Nos. 2,465,319 and 3,047,539.
U.S. Pat. No. 3,937,757 teaches that the tracking resistance of poly(1,4-butylene terephthalate) compositions can be improved by the addition of from 5 to 50% by weight of polyolefins or ethylene copolymers, containing at least 50% by weight of ethylene units, thereto.
U.K. Patent Application GB 2,011,443 describes high impact strength compositions comprising linear polyester resins and from 0.1 to 4.5% by weight of a copolymer of ethylene and vinyl acetate. Preferred such compositions can, on the one hand, can comprise copolymers containing "more than 50% by weight of vinyl acetate", and, on the other hand, "50% or less by weight, vinyl acetate". With respect to the latter, special mention is made of the ethylene-vinyl acetate copolymer containing 52% by weight vinyl acetate (Vynathene EY 904, sold by U.S.I. Chemicals). U.S. Pat. No. 3,580,965 describes high impact strength compositions comprising polyesters and alpha-olefin-vinyl ester copolymers containing in the copolymers from 30 to 99% by weight of units derived from the olefin.
U.S. Pat. No. 4,322,333 discloses reinforced copolyesters including minor, effective amounts of a copolymer of ethylene and vinyl acetate to improve impact strength.
U.S. Pat. No. 4,639,486 discloses flame retardant compositions comprising blends of a polyetherimide ester and a halogenated flame retarding material, optionally containing a modifier resin selected from condensation polymers and addition polymers; ethylene-vinyl acetate copolymers are not among those mentioned.
Vinyl acetate-ethylene polymerizates containing nominally 40 and 30% by weight of ethylene derived units are commercially available from Wacker-Chemie GmbH Munich, Germany under the Registered Trademark VAE. Such are recommended for use alone and in blends with other polymers, e.g., vinyl chloride polymers and polyolefins. A related commercially available copolymer of vinyl acetate and ethylene is sold by DIC Americas, Fort Lee, N.J., U.S.A., under the Registered Trademark EVATHLENE.
It has now been discovered that polymer blends comprising polyetherester resins, polyetherimide ester resins, alone, or combined with polyester resins or mixtures of any of them or of polyester resins alone with copolymers of alpha-olefins and vinyl esters of saturated aliphatic organic acids over a broad composition range will surprisingly provide improved compressibility, elasticity, low temperature impact strength, ultraviolet light- and chemical-resistance. Addition of the copolymers is also found to provide desirably lower Shore hardness, improved dynamic fatigue properties, paintability, extrudability and injection moldability. Elastomeric character especially is improved with polyester-polyether block copolymers. The new compositions can also contain reinforcing fillers and/or flame retardant agents.